Gilead Sciences, a company in the US was thought to have a treatment for Covid-19, went up 15% in a 2 day period because of the excitement surrounding their antiviral drug... Their market cap was $100 billion, so it went up $15 billion just on the Covid-19 drug... Recently it has been shown the drug has shown no benefit... Mesoblast has gone up $300m on the prospect of a treatment which IMO has greater potential
